A new electronics project! It’s a simple circuit that just keeps track of base health for Star Wars Unlimited (SWU) trading card game. This was my first time making/ordering a PCB, and I learned a lot along the way.

Problem Statement

To keep track of your base health in SWU, people usually use little damage tokens (in increments of 1/3/5/10), or dice. But I don’t like these.

I don’t like looking through a pile of tokens for the correct damage token, and dice never seem to cooperate with me. So instead of dealing with that, I decided it could be fun to build a little circuit that displays the current health. All the circuit needs to do is display the health and count up and down.

There’s already existing mobile apps, and there’s a little hockey puck like object you can buy that keeps track of base health, but I figured this project would also be a good chance for me to build and order my first PCB (printed circuit board).

Version 1 (Arduino + 16x2 LCD)

The simplest version, and the ugliest. I had one of those Arduino starter kits that had some buttons and the 16x2 LCD. So I wired them together and glued them onto some piece of wood I found downstairs.

Ugly but I just wanted to get the quickest version out to see if there was any value to this idea. I brought it to the local store I play at, used it once, and then put it back into my backpack. It was way too bulky to use, but the idea seemed reasonable.

Version 2 (ICs)

It seemed a little overkill to use a Arduino kit just to count up and down. I did some googling, and it turns out there’s ICs that pretty much do everything I need. Maybe I could get the power consuption to be trivial too and power off a coin battery.

Specifically:

• 74LS48: 7seg display driver from BCD
• 74LS192: Up/Down Counter
• 74LS14: Hex Schmitt Triggers for debouncing

But, this circuit was kind of complex! All those ICs take up a lot of space, the 7-segs are kind of ugly. It would never be that small.

It’s also annoying to debug the circuit and hard to expand.

Version 3 (PI Pico + Breadboard)

The first usable version! I decided to try out the Pi Pico Microcontrollers. They’re made by the Raspberry Pi people, but instead of being a microprocessor it’s just a microcontroller.

They’re pretty neat, and you can program them in MicroPython using Thonny, which is super simple.

Around this time I also bought a 3d Printer (Bambu Labs P1S) to print a case and some other SWU accessories.

So I learned OpenSCAD and made a little shell for the breadboard and battery pack. I used this version for a few weeks.

Version 4 (PI Pico + PCB)

The goal was to make things smaller. So I swapped out the display to something smaller, found a smaller LiPo battery, and printed my first PCB!

The library I used for the display didn’t have a way to increase text size, so I used font-to-py to generate 48px text. Full code.

I again used OpenSCAD to make a little holder for the circuit ( code).

I used PCBWay for the PCB, it was very simple, I just went with all the defaults and it arrived 5 days later. You have to buy 5 and it ended up costing $60 in total, but overall very happy with the results.

I just finished it today, so haven’t used it for real, but it looks great.

Future

I’m not too sure if I’ll do another iteration, but if I do, I’ll probably do some combination of the following.

• Size
  • The Pico takes up a lot of room. But you can actually extract the Pico circuitry and place it directly on your own board. I think the total board size could be just the buttons and the screen.
• On/Off Switch
  • I think it’d be cool if the on/off switch was hanging off the side, not facing frontwards.
• Charge Controller
  • LiPo batteries are rechargable, so it’d be cool if I could charge the device via USB.
• eInk display
  • I want to test it, but maybe it’d be cool to have an e-ink display for lower power usage
• Trigger/Interrupts
  • The code is currently using a while loop to check for inputs, instead I should register interrupts and keep the decide in lower power mode
• Wifi/History
  • It’s common to sometimes want to see what the health was previous. So maybe having a way to teather your phone and see the health values over time?

Conclusion

I’m very happy with the results of the project! I always use the device now when I play SWU. I also feel very powerful now that I can order my own PCB circuits and do my own 3d-Print modeling for whatever my heart desires.

Off to the next project! (Can we calculate which SWU cards are above curve? :evil-grin:)